F550 WKM went down like a sack of bricks!!!




yakjock

yakjock

Member
Droider said:
Sounds like an esc/motor failure OR a loose or bad bullet connector. Gues the bullets ripped when the arms broke. The 20 second before twtci leads me to this conclusion.. Have u checked the battery? After the first flight did you check motor / esc temps?

Dave
Click to expand...
Actually the bullet connectors were all still connected. I have made a check of all the soldering on the connections on the ESC's & Motors & found that one of the solder connections on the motor bullet connections of one of the broken arms looks like it (may) have a dry joint. This may have been the cause but the more I think about it the more I think it may have been the GoPro wifi backpack that was the more like to be the cause even though I have done 30+ flights with this copter in exactly the same setup as it was yesterday with no problems.
 


D

Dewster

Member
It could have been a prop failure. What props were you using? I lost my flat hexa in a similar fashion. I was climbing and then I heard a snap (which I immediately knew was a prop snapping) and my craft pitched violently 90 degrees and dropped from the sky. I had failsafe enabled so that the motors would shut off when the craft's pitch angle was over the ?? specified degrees.

If you lose a prop on a flat hexa, or quad you are pretty done.

I'm currently working on a Y6 hoping for redundancy.
 



DesJardins

DesJardins

Member
So I have done 2 tests (far from a decent pool of tests) but will do at least 10.

Gains set at above 120-140 the quad is VERY twitchy and wants to tip/roll in flight and literally just a hover when a gust of wind hits.
Gains down to about 90% and to tendancies.

Many more tests to come today
 

Bowley

Bowley

Member
yakjock said:
Actually the bullet connectors were all still connected. I have made a check of all the soldering on the connections on the ESC's & Motors & found that one of the solder connections on the motor bullet connections of one of the broken arms looks like it (may) have a dry joint. This may have been the cause but the more I think about it the more I think it may have been the GoPro wifi backpack that was the more like to be the cause even though I have done 30+ flights with this copter in exactly the same setup as it was yesterday with no problems.
Click to expand...



I had an X650 go down, I found a solder joint parted on the undamaged side of the airframe, in the absence of any other explanation and the fact that I cant reproduce the fault, I think this solder was the cause rather than a result of the crash. must watch those solder joints. I'm thinking of doing more crimping, done right it can be more reliable, I dont recall doing any soldering on actual wiring on full scale aircraft when I when I was a aircraft tech, all wiring was crimped.
 

Coomkeen

Coomkeen

Member
Yes, agree Bowley.
In electronics all my life, and crimped joints are more reliable than solder where movement is concerned.
In fact we did some tests, and you can make a crimped joint more unreliable by soldering it :(


Ron

EI8GMB - G6IWK
www.bandonmodelflyingclub.com
 

K

ksrimoungchanh

Member
Went out today.. my WKM F550 twitched often.. I did not hear the ESC chirping, but it twitch pretty violently for a bit. brought it back and grounded it till I could get some ideas.

looked at the banana plug from the DJI 2212 to the DJI Opto, I notice some of the plugs was much looser then the others. What are my options to get this to tighten or connect better? If I look at the plugs, there is an outer ring that swivels. I notice when the plugs are attached to the ESC, I can wiggle it just a bit, enough difference between some of the others.

What can I do to get this to fit better?
Also, is there an instructions on how to test ESC's?

Thanks in advance,

KS
 

D

DLien

Member
Hi Guys,

Any thoughts about what happen here? http://youtu.be/60qAo__-fYA

The video is just the last 30 seconds or so of a 5 minute flight. The crash occurred in Atti mode while using course lock. It departed levelish, forward flight and rolled sharply to the left just before the crash. I have the transmitter set up so it is impossible to get into manual mode accidently. Aside from breaking the left leg of the landing gear, there isn’t much other damage to repair.

The 550’s total weight is just short of 2700 grams with the aeroxcraft gear and the GoPro on a 2 axis mount. I am running a 4S 5000mah battery and Graupner 10X5 props, which I have been very happy with. I have been powering the servos for the camera mount directly from the MC.

I have had about 20 or 30 uneventful flights over the past few weeks with this set up. I did notice a sharp snap in roll 2 flights back. The 550 rolled sharply perhaps 20 or 30 degrees and just as quickly regained normal flight. I was descending at the time and assumed that it was a vortex ring issue.

Thanks,
Don
 
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Roger Ramjet

Roger Ramjet

Member
I am very concerned. The same this happened to me yesterday! I was in a hover on my second flight, ATT mode at about 100 feet. The Quad was stable and I started walking towards the quad in order to position myself underneath. Absolutely no radio inputs. All of a sudden, without any warning, it flipped upside down (rolled right) and accelerated towards the ground for 1 seconde then it recovered by itself and went back in a hover.... Needless to say that I landed on the spot and terminated the flight for the day! I had done exactly the samr 2 days ago but I was hovering at 5 feet... I plummetted straight to the ground, breaking the GPS pole. Took everything out, even the NAZA autopilot was verified for internal broken components and all was in good order. I suspect one of the DJI OPTO 30 amps ESC has a broken/loose connection. I will take the heatshrink out, inspect and report the results. IT IS BAD BECAUSE I CANNOT FLY MY QUAD AS IT IS UNRELIABLE, I HAVE A QUAD AND IT IS LIKE NOT HAVING ONE... ANY OTHER SUGGESTIONS, ANYONE? HAVE YOU EVER EXPERIENCED THIS?

DJI F450
NAZA, GPS
HITEC 9 Aurora (a dream radio)
Standard DJI motors (9212) and props (10 X 4.5)
 

K

ksrimoungchanh

Member
So, I got mine back and it showed the same twitching. Here is what I did.

I took my rotors off, power on the TX and F550 with no motors, started the motor to spin. I turned the F550 upside down so that the ESC was easily accessible... Then I went one by one and wiggled on the cable from the motor to the ESC.

I found that 2 of my ESC had a cable that would cause some weird things to happen.. like loose connection. Even though it felt like it won't come off, I could easily roll the plug while it was in the ESC.

I then marked those plugs.. powered everything off, and went and unplugged those ports to get a better look.

I ended up pulling the little copper swivel tensioning ring and put a dab(very little) of solder on the plug. Then I replaced the ring pushed the motor plug back into the ESC and notice it was tight and would not spin.. I ended up doing it to all the plugs on all the motors.

Took it out for a test yesterday.. it has not twitched. I have tried to fly aggressive, and just hover.. no twitch.

I am not sure if that was the issue but it seems to have worked so far. I am now 3 flights with no twitch. I was getting twitches every flight before.

basically, I just made sure my motor cables was tight and not able to spin when it was in the ESC plug.

I hope this helps others.

KS
 

C

chopper

Member
These units could benefit from some data logging. As complexity increases over time through the addition of new features , it will become ever more important to be able to identify the root cause of the failure. Logging also provides valuable data for post flight analysis to see where possible issues may be as well as indicate that all components are functioning within their individually designed parameters an tolorences. Some third party logging hardware is always an option, but I see a need to make logging a central feature to the main controlling unit. I could also see it benefiting the manufacturer in validating that hardware and firmware is working as expected on various platforms ( high volume field testing and validation). Additionally, determining what was pilot error vs system error can be more easily determined.
 

A

araines2750

Hexa Crazy
I eliminated all of the stock bullet connectors from my DJI motors. I also had a similar experience- The motor bullets were loose in the ESC.
I upgraded to new bullets on the motors.
I took the bullets out of XT-60 connectors. Gold plated, Easy to solder & PERFECT tight fit into the DJI OPTO 30 ESC.
I then used shrink wrap tubing at each ECS/ bullet to be double sure.
I considered direct solder connection to the ESC & motor, but wanted to be able to replace a motor if needed without soldering to the ESC.

I suggest that anyone who has stock DJI motor bullets upgrade as this is something that could cost you BIG $$$ if it causes a crash.

I gave this tip to Robert at DJI USA / UAV Products as well.

I will upload photos later.
 

DesJardins

DesJardins

Member
I have all the same tendancies which may have caused mine to go down also.
For now I'll do a quick fix of making the bullets tighter as mentioned to see if my twitch still exists.

Thanks for the info
 

K

ksrimoungchanh

Member
@ araines2750

Interesting that the resellers should consider suggestions like these. I also have giving this information to the reseller I am working with. Either they are just too busy to think about suggesting the replacement of the stock bullets or quickly mentioning to keep an eye out for symptoms or it goes agains their sales numbers and would rather just not.

I am new to the rc world, but have been reading about all these twitches, etc.. I have only hear from users suggesting fixes.

though my twitches have been gone since I did this, I am still always looking for suggestions from resellers and users community alike for better/smoother flights.

thanks for confirming same experience as mine.

KS


araines2750 said:
I eliminated all of the stock bullet connectors from my DJI motors. I also had a similar experience- The motor bullets were loose in the ESC.
I upgraded to new bullets on the motors.
I took the bullets out of XT-60 connectors. Gold plated, Easy to solder & PERFECT tight fit into the DJI OPTO 30 ESC.
I then used shrink wrap tubing at each ECS/ bullet to be double sure.
I considered direct solder connection to the ESC & motor, but wanted to be able to replace a motor if needed without soldering to the ESC.

I suggest that anyone who has stock DJI motor bullets upgrade as this is something that could cost you BIG $$$ if it causes a crash.

I gave this tip to Robert at DJI USA / UAV Products as well.

I will upload photos later.
Click to expand...
 


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